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The rapid acceleration of digitalization has fundamentally transformed the manner in which contracts are formed. In particular, the rise of e-commerce, remote working practices, and service relationships conducted through digital platforms has made the execution of contracts in electronic form increasingly indispensable. This development has, in turn, given rise to the concept of the electronic signature. Executing contracts electronically not only enhances transactional efficiency but also provides significant savings in time and cost compared to traditional methods. Nonetheless, the legal validity of electronically concluded contracts - and the conditions under which they become binding - remains a subject of discussion in both practice and scholarly commentary.
1. Legal Framework: Turkish Code of Obligations and the Electronic Signature Law
Article 12 of the Turkish Code of Obligations ("TCO") provides that parties are free to determine the form of their contracts, unless a specific form requirement is mandated by law. Accordingly, the principle of freedom of form constitutes the general rule under Turkish law with respect to the validity of contracts. In this context, what is essential is the parties' mutual and concordant declarations of intent.
While freedom of form is the general rule, the TCO exceptionally subjects the validity of certain contracts to specific form requirements. For instance, an assignment of receivables agreement (TCO Art. 184) must be executed in writing.
As stipulated under the TCO, contracts that are required to be executed in written form must bear the signatures of the parties assuming the obligations. Indeed, Article 15 of the TCO provides that "The signature must be affixed by the obligor in his or her own handwriting," thereby defining the signature element as an essential component of the written form requirement. However, with the advancement of technology, it has been recognized that a signature is no longer limited to a handwritten mark executed in physical form; identity-verification methods performed electronically may fulfill the same legal function. In this regard, the subsequent sentence of the same article - "A secure electronic signature shall have the same legal effect as a handwritten signature" - expressly affirms the validity of electronic signatures at the level of a general legislative provision.
On the other hand, the principal legal framework governing the matter was established with the enactment of the Electronic Signature Law No. 5070 ("ESL"). Article 5 of the ESL, through the provision stating that "A secure electronic signature shall have the same legal effect as a handwritten signature," ensured the explicit recognition of the secure electronic signature within the legal system for the first time, thereby providing the initial statutory basis for its equivalence to a handwritten signature. Nevertheless, the subsequent sentences of the provision set forth certain limitations on the use of secure electronic signatures. Pursuant to Article 5/f.2 of the ESL, "legal transactions that are subject to an official form or a special ceremony under the law, as well as bank letters of guarantee and guarantee instruments issued by insurance companies domiciled in Türkiye, may not be executed by secure electronic signature." This exception clearly demonstrates that, although the legal validity of secure electronic signatures constitutes the general rule, it is not absolute.
Accordingly, when Articles 15 of the TCO and 5 of the ESL are considered together, it can be concluded that a contract subject to the written form requirement satisfies the formal validity requirement if it is executed using a secure electronic signature.
2. The Concept and Types of Electronic Signatures
According to Article 3 of the ESL, an electronic signature is defined as "electronic data that is added to or logically associated with other electronic data and is used for the purpose of authentication." In practice, this concept encompasses a wide range of applications, from digitally affixing a signature on a computer screen to biometric signatures on mobile devices, typing one's name under an email, or clicking an "I approve" checkbox. However, this diversity does not imply that all electronic signatures carry the same legal effect or are legally valid. As regulated by Articles 15 of the TCO and 5 of the ESL, only a "Secure Electronic Signature" produces the same legal consequences as a handwritten signature.
Within this framework, electronic (digital) signatures are generally classified into two main categories in practice.
a. Secure Electronic Signature: Pursuant to Article 4 of the ESL, a secure electronic signature is a signature that meets specific technical criteria, is based on a qualified certificate, and is created under the exclusive control of the signatory. As it ensures both authentication and data integrity, a secure electronic signature holds the same legal validity as a handwritten signature.
Pursuant to Article 4 of the ESL, in order for an electronic signature to be considered "secure," it must meet the following conditions:
- The signature must be unique to the signatory;
- The secure electronic signature creation device must be under the sole control of the signatory;
- It must be based on a qualified electronic certificate;
- Any subsequent alteration of the signed electronic data must be detectable.
These characteristics are of critical importance for determining the identity of the signatory and ensuring the integrity of the signed document. Accordingly, by virtue of its technical infrastructure, a secure electronic signature guarantees the principles of "non-repudiation" and "immutability."
b. Simple Electronic Signature: This type of signature is used for authentication purposes but does not possess the technical security features required under Article 4 of the ESL. Simple electronic signatures typically appear in forms such as a signature image uploaded via a browser or signatures executed on touchscreen devices (e.g., DocuSign, Adobe Sign, HelloSign [Dropbox Sign], Skribble, etc.). In the doctrine, there are differing opinions regarding the legal validity of signatures falling within the scope of simple electronic signatures.
According to view that recognizes the validity of simple electronic signatures, under Article 15 of the TCO, a signature constitutes a mark made by the obligor in his or her own handwriting[1]. This mark may take the form of a name or designation, and what is crucial is that it is created with the intention of signing. The provision focuses solely on this essential element of the signature and does not impose any specification or limitation regarding the object, surface, or instrument upon which the signature must be affixed. Consequently, according to this view, a signature may be placed on any surface, thereby satisfying the written form requirement. Within this framework, based on the exceptional provision of Article 14/2 of the TCO, which allows "texts sent and retained via confirmed fax or similar means of communication" to substitute for written form, it can be argued that a manually executed signature on a screen may, under certain conditions, fulfill the written form requirement just as a signature on a faxed document would. However, for this interpretation to be accepted, the electronically created signature must be transformed into a verifiable, "transmitted, confirmed, and retainable" text; a mere screenshot or a signature affixed to a device surface alone may not suffice to meet the written form requirement.
In contrast, the majority view in the doctrine, which holds that simple electronic signatures are not valid, asserts that such signatures do not satisfy the written form requirement and may only be considered as "prima facie evidence." Indeed, signatures created solely through digital means currently lack statutory support or binding legal effect under Turkish law, as these signatures do not provide for a systematic oversight mechanism by administrative or official authorities. Furthermore, the Court of Cassation (Yargıtay) has not yet established direct precedent regarding the legal validity of digital signatures in Türkiye.
3. Conclusion
In conclusion, contracts executed electronically have become a fundamental element of modern commercial life, and the development of electronic signature technologies has brought about a profound transformation in contract law. While this transformation enables contracts to be concluded more rapidly and efficiently, it also introduces new responsibilities and requires careful attention to ensure legal validity and maintain trust between the parties. Accordingly, for each type of contract, it is of paramount importance in practice to carefully examine the form and validity requirements, taking into account the type of signature, the method of its creation, and the relevant technical security features.
Turkish law provides a solid legal foundation for this digital transformation by recognizing secure electronic signatures as equivalent to handwritten signatures. Pursuant to Article 4 of the ESL, a secure electronic signature that meets specific technical criteria ensures both authentication and data integrity, thereby reinforcing legal certainty between the parties and safeguarding the validity of contracts subject to the written form requirement. However, in practice, it is important to note that the key distinction with respect to validity lies between a "simple e-signature" and a "secure e-signature."
Footnote
1 Doç. Dr./Assoc. Prof. Dr. Zekeriya Kurşat, Yazılı Şekil Şartının Unsuru Olan İmzanın Elektronik Ekrana Atılmasını Etkisi , chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://dergipark.org.tr/tr/download/article-file/327269#:~:text=Bu%20durumda%20elektronik%20ortamda%20at%C4%B1lan,harici%20bir%20unsura%20ihtiya%C3%A7%20duyulmamaktad%C4%B1r.#330073]-327269.pdf , date of access: 10.10.2025
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